1. Field of the Invention
The present invention relates to a real image type view finder.
2. Description of Related Art
In a conventional real image type of view finder, an inverted image, which is formed by a positive objective lens group and a positive condenser lens group, is erected by an image erecting optical system so that the erect image can be viewed through a positive ocular lens group (i.e., eyepiece group). The condenser lens group is usually located in the vicinity of the focal position of the objective lens group. Consequently, the condenser lens group contributes little to the formation of an inverted image. Formation of the primary image (i.e., primary convergence) is mainly effected by the objective lens group. The condenser lens group has little power to form the primary image. Consequently, it is difficult to correct an aberration of the image formed by the primary convergence, particularly in recent compact cameras having a small view finder with high power variation.
In a camera having a view finder separate from a photographing optical system, the parallax error between the view finder and the photographing optical system must be corrected upon assembly, so that parallax error does not occur at a specific object distance (i.e., reference object distance). There are various known parallax correcting mechanisms. For example, in a conventional real image type view finder, parallax error correction is carried out by the adjustment of an angle of a mirror provided within the objective lens group. In the angular adjustment of the mirror, the field of view within a plane including the optical axis of light incident upon the mirror and the optical axis of light reflected by the mirror and, accordingly, the reflection angle of the reflected light can be adjusted, but if the light is out of the plane, an inclination of the image takes place.
Furthermore, it is also known to execute parallax compensation by the adjustment of the displacement of the field frame. However, in this parallax error compensation system, a prism which constitutes the image erecting optical system must be large enough to entirely cover the adjustment range of the displacement the field frame, thus resulting in a large view finder.